Mayflies

1. Mayflies Order: Ephemeroptera

2. Life Cycle • Hemimetabolous (egg, naiad, adult) • Naiad: aquatic, gill-breathing nymph • Nymph: larva of an insect without a pupal stage • 1-3 generations / year; 12-50 molts! • Subimago stage (“duns”) • Short-lived adult stage (“spinners”)

3. General Morphology Naiads: Large eyes Chewing mouthparts Gills on abdomen Usually 3 tails Adults: Soft-bodied FW large, triangular, veined Elongated forelegs, tails

4. Naiad Morphology • Well developed eyes • Slender antennae • Well-developed legs, with one claw • Gills (abdomen sides) • Fore-wing pads may be present • Usually 3 caudal filaments (tails)

5. Adult Morphology • Elongate, very soft • FW large, many veins • HW small or absent • Wings above body at rest • Mouthparts vestigial • Fore-legs very long • 2-3 long tails

6. Systematics • 2 suborders: Schistonota (“Splitbacks”) and Pannota (“Fusedbacks”), refers to wing pads • 3 superfamilies in each suborder • 17 families • Characters used include gill structures, mouthparts, hairs/spination: these change with age!

7. Suborder Schistonota“Splitback Mayflies” • Larval fore wing pads free for at least half of the pad length • Thorax usually slim and delicate • Gill series usually well developed on sides of abdomen • Active and diverse mayflies

8. Suborder Schistonota Superfamilies Baetoidea (6 families) Leptophlebioidea (1 family) Ephemeroidea (5 families)

9. Superfamily Baetoidea Families: Siphlonuridae (“Primitive Minnow”) Metretopodidae (“Cleftfooted Minnow”) Ametropodidae (“Sand Minnow”)* Baetidae (“Small Minnow”) Oligoneuridae (“Brushlegged”) Heptageniidae (“Flatheaded”) * Western. 3 species, not covered here.

10. Siphloneuridae(“Primitive Minnow Mayflies”) • Streamlined • Long axis of head vertical • Fore legs w/o hairs • Platelike gills oriented dorsally • Sharp spines on posterior abd. Segments Ameletus sp.

11. Metretopodidae(“Cleftfooted Minnow Mayflies”) • Strong swimmers • Medium/large rivers • 2 claws on foreleg Siphloplecton basale

12. Baetidae(“Small Minnow Mayflies”) • Small, 9-10 mm • Variety of habitats • Good swimmers • Some tolerate polluted water • Some with 2 tails! Callibaetis (left) Pseudocloeon (right)

13. Baetidae • Fall emergence in some species • Note rounded 9th abdominal segment Baetis longipalpus (Antennae more than twice width of head)

14. SubimagoBaetistricaudatus • Shorter front legs • Dull wings • Fringe of ciliated hairs on wings • Dun, “little iron blue quill”

15. AdultBaetistricaudatus • Longer front legs • Brighter colors • Spinner, “blue winged olive (applies to Baetids in general)”

16. Oligoneuridae(“Brushlegged Mayflies”) • Streamlined shape • Filter feed with hairs on front legs • Swift currents Isonychia sadleri

17. Isonychia Filter Feeding

18. Isonychia bicolor“Leadwing Coachman,” “Mahogany Dun.”

19. Isonychia sadleri imago

20. Heptageniidae(Flatheaded Mayflies) • Greatly flattened head, legs • Clinging under rocks • Often very long tails Stenonema rubrum (Note unique 7th gill structure)

21. Heptageniidae(7th abdomimal gill) S. rubrum

22. HeptageniidaeStenacron interpunctatum • Subimago called “Light Cahill” • 7-12 mm, excluding tails, legs • May-September • Note relatively short legs of subimago

23. Heptageniidae S. Rubrum imago

24. Heptageniidae • Cup-shaped to cling • Bright red gill color Rhithrogena sanguinea (Ventral view)

25. Superfamily Leptophlebioidea Family Leptophlebiidae (“Pronggills”)

26. Leptophlebiidae(“Pronggills”) • Gills on segs. 1-6 or 1-7 • Gills double or forked • Prefer crevices Leptophlebia sp.

27. Leptophlebiidae • Subimago called “dark blue quill” • Small (6-8mm excluding tails, legs) • August-October • Note long legs of imago Paraleptophlebia debilis imago

28. Superfamily Ephemeroidea Families: Behningidae (“Tuskless Burrowers”)* Potatamanthidae (“Hacklegills”) Polymitarcyidae (“Pale Burrowers”) Ephemeridae (“Common Burrowers”) Palingeniidae (“Spinyheaded Burrowers”)** *Southeast U.S. only **South only

29. Potamanthidae(“Hacklegills”) • Somewhat like Heptageniidae, but… • Gills unique, laterally oriented • Tusks, curve inward

30. Polymitarcyidae(“Pale Burrowers”) • Larvae in silt, stream banks • Adult with nonworking legs • Sexually mature subimago • Subfamily id uses frontal processes Polymitarcyinae Ephoron sp. Campsurinae

31. Ephemeridae(“Common Burrowers”) Ephemera sp. • Large, 12-32 mm • Tusks lack spines, curve up & out • Burrow in silt-sand in rivers or lakes Hexagenia sp. Ephemera sp.

32. Hexagenia limbata(“Michigan Caddis”)

33. Ephemera guttulata subimago(“Green Drake”) (18-21 mm + tails)

34. Suborder Pannota“Fusedback Mayflies” • Naiad with wing pad fused to thorax for at least half of pad length • Thorax robust • Gills lay on abdomen • Operculate (covering) gills

35. Suborder Pannota Superfamilies Ephemerelloidea (2 families) Caenoidea (2 families) Propistomatoidea (1 family)

36. Superfamily Ephemerelloidea Families: Ephemerellidae (“Spiny Crawlers”) Tricorythidae (“Little Stout Crawlers”) gills

37. Ephemerellidae(“Spiny Crawlers”) • 5-15 mm + tails • dorsal spines on head, thorax, abdomen • No gills on segment 2 • Gills lie on abdomen Serratella sp. (left) Timpanoga sp. (right)

38. Tricorythidae(“Stout Little Crawlers”) • 3-10 mm + tails • Hind wing pad absent or minute • Gills on seg. 2-6 • Gills on 2 are triangular and operculate

39. Superfamily Caenoidea Families: Neoephemeridae (“Large Squaregills”) Caenidae (“Small Squaregills”)

40. Caenidae(“Small Squaregills”) • Widespread and common in east • Small, 3-4 mm + tails • No hind wing pads • Operculate gills overlap slightly Caenis simulans

41. Superfamily Propistomatoidea Family Baetiscidae (“Armored Mayflies”)

42. Baetiscidae(“Armored Mayflies”) • Banks of medium streams • Striking thoracic shield